1. Field of the Invention
The present invention relates to an antenna apparatus used in Ultra Wide Band (UWB) communication.
2. Description of the Related Art
UWB communication enables ultra fast communication by using a GHz frequency band. In 2002, the U.S. Federal Communication Commission (FCC) approved usage of the UWB. Since then, an application of the UWB to a portable electronic device and a high precision positioning system has been expected. An ultra wide frequency band antenna apparatus, which includes an inverted teardrop-shaped antenna element and is suitable for a GHz frequency band, has been developed.    Patent Document 1: Japanese Patent Laid-Open Publication No. 2004-129209
The inverted teardrop-shaped antenna element is connected to a ground element, and is insulated from the ground element.
Since a conical portion of the inverted teardrop-shaped antenna element is smaller than a hemispherical portion of the inverted teardrop-shaped antenna element, joint strength between the antenna element and the ground element may be insufficient.